Liquid soluble gas sealed cooling system

ABSTRACT

An apparatus that first and second volumes are fluidly separated by a combination of a first second and a second sections, where the first section is insoluble to a cooling liquid and the second section is soluble to the cooling liquid. In the event of a leak of coolant liquid, the second sections dissolve, forming a fluid path from the first volume to the second volume. The coolant liquid may then escape the first volume in spaces that result from the dissolution of the second sections.

BACKGROUND

Large computer, storage, or networking server systems, typically used indatacenters, require cooling. Often times liquid cooling systems areused to cool these systems. The liquid cooling system is typically aclosed loop system that communicates chilled cooling fluid (coolant) toa cooling plate that is thermally coupled to a heat load (e.g.,electronics) that requires cooling. The cooling plate transfers heatfrom the heat load to the coolant, and the heated coolant iscommunicated to a heat exchange for chilling.

Typically a rack or a chassis that is liquid cooled also includesmultiple different airflow domains. An airflow domain, or more generallya gas flow domain, is a volume that is sealed from other gas flowdomains and through which a gas (typically air) can be maintained at apositive pressure relative to ambient atmospheric pressure. There areliquid and air cooled equipment that require two or more gas flowdomains that are independent and fluidly isolated from each other (e.g.,fluidly sealed relative to each other). When a liquid coolant leakoccurs in one of the domains, however, the coolant will tend to collectin the domain, as the domain is fluidly sealed from the other domainsand from the external atmosphere.

To prevent pooling of coolant, some systems have unsealed airflowdomains, typically through an unsealed drain outlet, to allow drainagefrom the airflow domain having liquid cooling components. This design,however, negatively impacts the air cooling effectiveness the airflowdomains that are in communication with the unsealed drain outlet.Another design involves separate drainage paths for each domain. Thisdesign is more complex than the prior design, however, and is difficultto scale.

SUMMARY

The technology in this patent application is related to systems andmethods for integrating liquid soluble seals/gaskets in air and watercooled electronic equipment to prevent coolant pooling within the volumethat defines an air flow domain.

In general, one innovative aspect of the subject matter described inthis specification can be embodied in an apparatus including a housinghaving a drain surface, and having defined within: a first volume, and asecond volume that is fluidly isolated from the first volume by aseparating member, wherein the separating member includes a firstsection that is insoluble to a cooling liquid and one or more secondsections, wherein each of the one or more second sections is soluble tothe cooling liquid; and wherein: the first volume defines a gas flowdomain through which a gas may flow; the first volume is positionedabove the second volume, and the drain surface is a bottom surface ofthe second volume; and when the second sections of the separating memberare dissolved by the cooling liquid, open spaces are formed in theseparating member and the cooling liquid drains from the first volumeinto the second volume.

Another innovative aspect of the subject matter described in thisspecification can be embodied in an apparatus including a first airflowdomain, a liquid cooling exchange system located within the firstairflow domain that includes a cooling liquid that is circulated withinthe liquid cooling exchange system; and a second airflow domain that isfluidly separated from the first airflow domain at least in part by agas seal component, wherein the gas seal component comprises a liquidsoluble material that is soluble to the cooling liquid.

Particular embodiments of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. The liquid soluble air seals/gaskets dissolve whenthey come into physical contact with coolant, thus allowing forautomatic opening of a drain path when the leak occurs. There is no needfor an electro-mechanical switching device, or purely mechanicalswitching device, to open a drain path; instead, inexpensive andsacrificial sealing material is used to plug the drain path and seal thedomain. In the event of a leak, the sacrificial sealing materialdissolves, allowing the coolant to drain. The drain locations and drainpath may thus be positioned virtually anywhere in the airflow domain, asdesign factors relating to drain pipes, pumps, etc., are eliminated.Instead, only a hole or space need be created, and then plugged with thesacrificial sealing material, which facilitates multiple drain pathdesign options.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are cross-sectional and top sectional views of anapparatus, such as a server rack, that employs a liquid soluble gassealed cooling system.

FIG. 1C is a cross-sectional view of the apparatus of FIGS. 1A and 1B,and further illustrating a coolant leak prior to dissolution ofsacrificial sealing material.

FIG. 1D is a cross-sectional view of the apparatus of FIG. 1C,illustrating a drain path after dissolution of the sacrificial sealingmaterial.

FIGS. 2A and 2B are cross-sectional and top sectional views of anapparatus implementing another implementation of a liquid soluble gassealed cooling system.

FIGS. 3A and 3B are cross-sectional and top sectional views of anapparatus implementing yet another implementation of a liquid solublegas sealed cooling system.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

This disclosure describes a liquid soluble gas sealed coolingarchitecture that provides a fluidly sealed airflow domain with liquidcooling components. The airflow domain is fluidly sealed, in part, bysections that are made of a sacrificial sealing material that is liquidsoluble to the coolant used in the liquid cooling components. Forexample, if water is the coolant, then the sacrificial sealing materialis made of a water-soluble material that dissolves when in contact withwater (or otherwise structurally fails) to unseal the fluidly sealeddomain and provide a drain path for the coolant.

The sacrificial sealing material may be used as one or more of seals,gaskets or plugs. When the sacrificial sealing material is dissolved,liquid is then allowed to flow through the drainage paths and drain fromthe equipment in a controlled manner. The liquid soluble sealingmaterial thus allows for airflow domains to be fluidly sealed duringnormal operation but become unsealed in the presence of a coolant leakto allow drainage of the coolant.

These features and additional features are described in more detailbelow.

FIGS. 1A and 1B are cross-sectional and top sectional views of anapparatus 100, such as a server rack, that employs a liquid soluble gassealed cooling system. The apparatus 100 includes a housing 102 having adrain surface 104, i.e., a surface in the downward direction of gravityrelative to other components and from which fluid may drain through adrain outlet 106. The drain surface 104 may be a bottom surface uponwhich the apparatus 100 rests, or, alternatively, may be an intermediatedivider below which are additional airflow domains.

The housing 100 includes various walls and structures that define afirst volume 120 and a second volume 140. The first volume 120 ispositioned above the second volume 140, and the bottom of the secondvolume 140 is defined by the drain surface 104.

The second volume 140 is fluidly isolated from the first volume 120 by aseparating member 150. The separating member 150 includes componentsthat are insoluble to coolant, and components that are soluble to thecoolant. In the example implementation of FIGS. 1A and 1B, theseparating member 150 includes a first section 152 that is insoluble tothe coolant, and one or more second sections, e.g., second sections 154and 156, that are soluble to the coolant.

The first section 152 may be a printed circuit board that includeselectronic components that, when powered, generate a heat load.Alternatively, the first section 152 may be a mounting structure uponwhich one more circuit boards, fans, or other electronic components maybe mounted and powered. In still other implementations, the firstsection 152 may simply be an interior plate or divider section, andelectronic components may be mounted elsewhere within the first volume120.

The second sections 154 and 156 are gas sealing component that are usedto fill a gap that exists between the side edges 160 and 162 of thefirst section 152 and respective side walls 108 and 110. The secondsections are sacrificial sealing material that dissolve when in contactwith the coolant. The type of sacrificial sealing material may depend onthe coolant used. For example, when water is the coolant, thesacrificial sealing material may be made from a biodegradable plantproduct, such as material made from grain sorghum or corn starch, thesame material that is used to make packing peanuts. Other materials thatmay be used include polyvinyl alcohol (PVA). More generally, thesacrificial sealing material is any material that dissolves when incontact with the particular coolant used, and when dry providessufficient striatal integrity at a normal operation temperature (e.g.,up to 140 degrees Fahrenheit/60 degrees Celsius) to provide a fluid(gas) isolation at a typical pressure differential between the airflowdomains 120 and 140.

The first volume 120 defines a sealed gas flow domain through which agas may flow. For example, gas in the volume 120 may be maintained at apositive pressure relative to ambient atmospheric pressure. As used inthis specification, the term “sealed” does not necessarily meanhermetically sealed or otherwise sealed in a manner that fluid (gas orliquid) may not escape. Instead, the term “sealed” means, in the contextof a domain, that a gas may be maintained at a pressure that is higherrelative to another domain or an external domain. Thus, the firstsection 152 and second sections 154 and 156 need not provide a truehermetic seal, but need only provide sufficient isolation to maintaingas flow within the domain.

Assuming the first section 152 is a printed circuit board, the firstsection 152 may be coupled to a heat dissipating component. Within thefirst volume 140 is a thermal coupler 170 and a cold plate 172. The coldplate 172 is coupled to a tubing 174 though which chilled cooling liquidis circulated. In operation, the electronic components generate a heatload that is cooled by the cooling system by coupling of the heat loadthrough the thermal coupler 170 to the cold plate 172. The first volume120 and the second volume 140 are fluidly isolated by means of the firstsection 152 and the second sections 154 and 156. In the event of acoolant leak, however, the second sections 154 and 156 will dissolve toallow for drainage of the coolant. Such a scenario is described withreference to FIGS. 1C and 1D. In particular, FIG. 1C is across-sectional view of the apparatus of FIGS. 1A and 1B, and illustratea coolant leak prior to dissolution of sacrificial sealing material ofthe second sections 154 and 156. FIG. 1D is the cross-sectional viewillustrating a drain path after dissolution of the sacrificial sealingmaterial.

FIG. 1C illustrates a leak occurring at the cold plate 172, and aresultant pooling of coolant 180 in the first volume 120. However,because the coolant 180 is in contact with the second section 154 and156, and because the second sections 154 and 156 are made of a materialthat is soluble to the coolant, the second sections 154 and 156 begin todissolve. Eventually the structural integrity of the sacrificial sealingmaterial fails, and a drain path opens from the first volume 120 to thesecond volume 140, as shown in FIG. 1D. The drain path is defined by thespaces that connect the first volume 120 to the second volume 140, andcreated by the dissolution of the sacrificial sealing material. Thecoolant 180 then collects on the drain surface 104 and drains throughthe drain outlet 106.

In the example implementation of FIGS. 1A-1D, the first section 152defines edge peripheries 160 and 162 that are separate from the sidewalls 108 and 110 of the housing 102. But other configurations can alsobe used. For example, in FIGS. 2A and 2B, an alternate implementation ofthe apparatus 200 includes a first section 252 that has multiple holesfilled by second sections 254, where each second section is made of thesacrificial sealing material.

By way of another example, in FIGS. 3A and 3B, an alternateimplementation of the apparatus 300 includes a first section 352 andsecond sections 354 and 356 that fill slots defined in the first section352. Still other configurations can also be used. For example, insteadof multiple gas seal components spaced apart from each other, a singlegas seal component can be used to fill a single space in the firstsection.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyfeatures or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments. Certain features that aredescribed in this specification in the context of separate embodimentscan also be implemented in combination in a single embodiment.Conversely, various features that are described in the context of asingle embodiment can also be implemented in multiple embodimentsseparately or in any suitable subcombination. Moreover, althoughfeatures may be described above as acting in certain combinations andeven initially claimed as such, one or more features from a claimedcombination can in some cases be excised from the combination, and theclaimed combination may be directed to a subcombination or variation ofa subcombination.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

What is claimed is:
 1. An apparatus, comprising: a housing having adrain surface, and having defined within: a first volume; and a secondvolume that is fluidly isolated from the first volume by a separatingmember, wherein the separating member includes: a first section that isinsoluble to a cooling liquid; and one or more second sections, whereineach of the one or more second sections is soluble to the coolingliquid; wherein: the first volume defines a gas flow domain throughwhich a gas may flow; the first volume is positioned above the secondvolume, and the drain surface is a bottom surface of the second volume;and when the second sections of the separating member are dissolved bythe cooling liquid, open spaces are formed in the separating member andthe cooling liquid drains from the first volume into the second volume.2. The apparatus of claim 1, further comprising: liquid coolingcomponents disposed within the first volume, including: tubing withinwhich the cooling liquid is communicated, the tubing sealed from thefirst volume; and a cold plate that is coupled to the tubing and thatprovides cooling to a heat load that is thermally coupled to the coldplate.
 3. The apparatus of claim 2, wherein: the first section includeselectronic components that, when powered, generate a heat load; and thecold plate is thermally coupled to the heat load.
 4. The apparatus ofclaim 3, wherein the first section comprises a printed circuit board. 5.The apparatus of claim 2, wherein: the first section is configured tohave mounted thereon electronic components that, when powered, generatea heat load; and the cold plate is thermally coupled to the heat load.6. The apparatus of claim 1, wherein: the cooling liquid is water; andthe second sections are water soluble.
 7. The apparatus of claim 6,wherein the second sections are made of a biodegradable plant product.8. The apparatus of claim 6, wherein the second sections are made ofpolyvinyl alcohol (PVA).
 9. The apparatus of claim 6, wherein: the firstsection defines a periphery that is separate from at least one side wallof the housing; and the one or more second sections define a gasket thatis interposed between the periphery of the first second and the at leastone side wall of the housing.
 10. The apparatus of claim 6, wherein: thefirst section defines one or more holes that each penetrate the firstsection and has an internal periphery; and the one or more sectionsections define plugs that each fill a respective hole in the firstsection.
 11. An apparatus, comprising: a first airflow domain: a liquidcooling exchange system located within the first airflow domain thatincludes a cooling liquid that is circulated within the liquid coolingexchange system; and a second airflow domain that is fluidly separatedfrom the first airflow domain at least in part by a gas seal component,wherein the gas seal component comprises a liquid soluble material thatis soluble to the cooling liquid.
 12. The apparatus of claim 11, furthercomprising computer electronics thermally coupled to the liquid coolingexchange system, wherein the liquid cooling exchange system cools thecomputer electronics.
 13. The apparatus of claim 12, wherein thecomputer electronics comprise a printed circuit board, and wherein thesecond airflow domain is separated from the first airflow domain by thegas seal component and the printed circuit board.
 14. The apparatus ofclaim 13, wherein the gas seal component comprises a gasket along atleast one side of an external periphery of the printed circuit board.15. The apparatus of claim 11, wherein the liquid soluble materialcomprises a water-soluble foam material.
 16. The apparatus of claim 11,wherein the liquid soluble material comprises a water-soluble syntheticpolymer.
 17. The apparatus of claim 11, wherein the second airflowdomain includes a liquid drain path.
 18. The apparatus of claim 11,wherein the second airflow domain is fluidly separated from the firstairflow domain by a structure that is insoluble to the cooling liquidand that includes spaces that are plugged by the gas seal component. 19.The apparatus of claim 11, wherein the gas seal component is a singlecomponent.
 20. The apparatus of claim 11, wherein the gas seal componentcomprises a plurality of separate gas seal components spaced apart fromeach other.